Our previous randomized clinical trials evaluated closed loop insulin delivery in over 120 subjects under FREE-LIVING UNSUPERVISED HOME settings in studies lasting 1 WEEK to 3 MONTHS (total closed loop operation 81,120 hours/3,380days/9.3 years). All studies used CAMBRIDGE model predictive control algorithm. We demonstrated the safety, efficacy, and acceptability of closed loop insulin delivery over short to medium long investigations. However, performance over prolonged period is unknown and is of interest particularly in young subjects given failure of other approaches to improve outcomes. The present project addresses the important question of LONG TERM closed loop use and will apply an Android-phone closed loop system directing insulin delivery by a next generation insulin pump. The system will be configured to protect against HYPOGLYCAEMIA in case of closed loop not being temporarily operational for reasons such as limited component connectivity. Specifically, we will evaluate the performance of 12 MONTH 24/7 CLOSED LOOP in CHILDREN AND ADOLESCENTS aged 6 to 18 years with type 1 diabetes under FREE-LIVING UNSUPERVISED HOME SETTINGS. We will use closed loop system comprising 640G PUMP and ENLITE 3 sensor (both Medtronic) and an Android phone running CAMBRIDGE MODEL PREDICTIVE CONTROL ALGORITHM. The system SAFETY will be ENHANCED by the use of predictive low glucose management, INTEGRATED on 640G pump, and suspending insulin delivery when hypoglycaemia is predicted even when Android-driven closed loop is not operating. In total, 130 PARTICIPANTS will be randomised to undergo either 24/7 closed loop or sensor augmented insulin pump therapy (65 participants in each group). The study will compare BIOMEDICAL, PSYCHOSOCIAL, and COST-EFFECTIVENESS of the two study interventions. HbA1c measured in central laboratory will be the primary endpoint. Biomedical outcomes (mean glucose, time in/above/below target and other related glucose/insulin metrics) will be complemented by assessments of psychosocial/human factors issues (focus groups and questionnaires) and cost utility analysis. The project will provide information to facilitate pivotl studies leading to REGULATORY APPROVAL, COMMERCIALISATION, AND REIMBURSEMENT of 24/7 closed-loop control.